New Project: Parallel Markup

Dear Fellow Inventors,

Elliot and I have decided to postpone working on the Fresnel lens until warmer, sunnier weather here in Austin.

In the meantime, I intend to create a new project, which I call "Sparmark", a human readable system for parallel markup.

Parallel markup is the idea of NOT modifying a document with markup but rather creating a separate, parallel document to hold markup which essentially represents a transformation of the original document.  When I studied this field some years ago, the research for it was not terribly advanced, and I thought it was a field in which amateurs such as ourselves could make a significant contribution.

I believe Ted Nelson has been the biggest contributor to this field with his idea of Transclusion.  I found this paper: Embedded Markup Considered Harmful http://www.xml.com/pub/a/w3j/s3.nelson.html to be a particular compelling and cogent expression of the problem.

In this post on New Year's Day I can't put down all of my ideas about this, but here is a summary:

• I think we should create an open-source project to create parallel markup standards and software tools that will make transclusion much easier.  I imagine Python to be a language particularly well-suited to this, although I have never used it. (My previous work on this was in LISP.)
• We must focus on creating a forgiving and human-editable markup.  In particular, I intend to draw inspiration from the markup that human copy editors do with a pencil.  The fact that we must deal with electronic texts should not prevent us from learning from the analog standards that copy editors have developed over decades.  XML is a terrible failure because it focused on software tools rather than human use.
• I'm going to go out on a limb and try to create some videos and other things to recruit others to be involved in this project.  This log is very lightly read.  I don't seem to be very good at affecting my fellow workers, but I intend to continue working on it.

Please contact me if you would like to help create a team to work on this project.

Change in plans: Going to Fresnel Lens

Elliot and I tested the polished panels weekend before last.

They functioned, but our calorimetric tests were a miserable failure.  We conclude that we can focus the rays but it is very hard to get them into the target.  We can probably toast bread well, because it is a nice, flat, target.  However, attempting to heat our jar of water was very ineffective.

However, we are not giving up.  Rather, we are now going to investigate using a large Fresnel lens, which Elliot happens to have.

No-Update update, and call for volunteers

I took the weekend off and then got sick.

However, my hope is this coming weekend we can really test the newly polished panels.  I have some hope that we can actually cook a 1/3rd of a hot dog, which will be a major breakthrough---and a long time coming, if you have been following this little project.

However, let me use this "dead air" to once again call for volunteers, or participants in this project.  It's really great working with Elliot, who is a fine mathematician and engineer.  However, I would love to get someone else involved in the project.

What needs to be done?  Well, in the first place we need people to join the conversation about what we are trying to do.  Is the idea of an demonstration project really worthwhile at all?  We need your help in working this through.

However, here are some other practical things that need to be done:

1. We need someone to design the cooking chamber in such a way that it actually is convenient to cook with.
2. We need someone to design the waist-high frame so that, just like a gas-powered grill, you can work at a convenient height and have little shelves to rest your food on as you prepare it on the grill.
3. We need someone to design the counter-balance that will let us use a Dobsonian telescope mount and keep the collector aimed at the son.
4. We need someone to start designing an electronic sensing and timing module.  For example, although it is not used by most people at the park, we would really like to be able to measure:

• The wattage produced by the collector,
• The internal temperature of food,
• The temperature history of a closed container (distinct from grilling, I know.)

Additionally, I would like to find someone who can figure out a "victory condition" to get our system installed somewhere.  For example, maybe you run a retreat center or something, and you like the idea of having a solar grill.  However, you need to be able, for instance, to cook 60 burgers an hour.  Or perhaps you are concerned about rain, or vandalism.  Basically, as in the design of any project, we have to do customer research, or marketing research.

One of my personal heroes is Buckminster Fuller.  I've ready everything he ever wrote, I think, and thought deeply about his life.  I would like to accomplish a fraction as much as he did.  But he made some mistakes.  He did now work hard enough to get his ideas accepted.  I am consciously not trying to create a new technology---I am trying to make an old technology acceptable.  In this, I need your help.  So, if you have any interest, or even just a comment, please comment or send me email (read.robert at gmail dot com).

Polishing Can be a Dirty Job

Dear Fellow Inventors,

Two weekends ago Elliot and I measured unpolished aluminum panels in our cooker and found that they were far less effective than aluminum foil panels.  We decided that we had to construct fully polished and correctly cut panels, both to measure them absolutely and to compare them to foil.

We found that polishing is rather difficult work.  There are videos on YouTube that show you how to do it, but a fundamental secret is that you need to the most powerful polishing tool you can get.  We bought one for about $200, a huge, heavy, dangerously powerful Hitachi tool pictured below.  Using this, I was able to polish all 4 panels in about 6 hours.  It is, however, a dirty, boring and time-consuming job.

The final result is a mirror-like, but not quite mirror-quality, reflective surface.  We hope to test the new oven with these panels soon, and I am optimistic we will have better performance than ever before.

Unpolished=bad. And we can toast bread.

Today Elliot and I tested the oven with the unpolished aluminum panels that we installed with the tensioning system last time.  They are ineffective.

Here are are timings and temperature measurements (Fahrenheit):

0:00 -- 79
1:00 -- 80
2:00 -- 80
3:00 -- 81
4:00 -- 81
6:00 -- 81

Close-up of polished panels installed on top of unpolished panels.

This is very disappointing, but accords with the subjective "hand test"---I could hold the palm of my hand at the target area for 25 seconds, which is longer than the others.  We then installed our mis-cut polished panels that have a near-mirror like surface.  The "hand test" lasted to a count of 13.  Here is the time measurement:

0:00 -- 92
1:00 -- 93
2:00 -- 94
3:00 -- 97
4:00 -- 98
5:00 -- 99
6:00 -- 100
7:00 -- 100
8:00 -- 100

Note that we adopted an experimental procedure of "stirring" the 2 cups of water with the thermometer, which made our temperatures much more stable.

We went inside for approximately 30 minutes to plot our next course of action, and when we returned the water was at 130F (we took it out and measured it very reliably.)  At this point, the oven was not aimed particularly well due to the apparent motion of the sun.  This was basically the same performance we got previously with the same miscut polished panels.

Our conclusion is: we really need to create properly polished, properly cut panels and test them.  That will be my mission for this week.

We performed two other interesting experiments.  We took 3 panels of posterboard that had foil glued to them via 3 distinct mechanisms: contact cement, rubber cement, and heated rubber cement.  We curled them (with tape) and left them in the sun.  All three developed some wrinkles.  The heated rubber cement seems to have the fewest wrinkles.  We bought some much stiffer poster board and Elliot is going to manufacture some new panels for us to test with additionally, in hopes of doing a side-by-side test of foil-on-board vs. polished aluminum.

Close-up of one of the panels

Cold rubber cement--large wrinkles.

Our three foil-covered posterboard panels, heating in the sun---showing developing wrinkles in all cases.

Finally, we stuck a piece of bread in the target area, aimed it, and left it alone.  We went back about 45 minutes later (we weren't really tracking time closely.) The oven had toasted the bread to browning, at least in some of the region. (Note that our target area is a 3" x 3" square, significantly smaller than a slice of bread.

Our toasted bread.

 It isn't visible but the whole 3" square was dry and staled (that is dehydrated---what we think of as toasted.)  Obviously, the burned part received more intense solar radiation.  Here is the back of the same slice, with the browning showing through.

This is, in fact, the first thing that we have eaten which we "cooked".

What we are trying to do with the Solar Oven

An advocate for the devil should challenge us with these questions:

• Why are you researching such fully understood technology?
• Why are you building something so small that it can't even cook a hot dog?
• Why are you using such a long, narrow collector?
• What can you hope to contribute to technology of solar cooking?

The theory of compound parabolic collectors is mostly understood.  It was initiated by Roland Winston (and perhaps others simultaneously) in the 70s, I think. We are not in much of a position to improve upon this theory. However, we can improve on the practice.  For example, I don't think very many actual example of 3-d parabolic compound collectors have been created and analyzed.  Certainly Elliot and I have found constructing our box-shaped collector challenging to make, and we have access to computers, a laser cutters, and most of the tools that we might need.  Constructing a revolved surface or an approximation to one is even harder to make.  We are in now in a position to build and test a surface of revolution, although we have no immediate plans to do so.

Along the same lines, one can construct an oven out of mirrors, unpolished aluminum, polished aluminum, and aluminum foil (we have tried all of these!)  but I have not found a resource that actually compares these reflectors from a practical point of view. I hope at least we can contribute to this kind of practical knowledge. I did not go to graduate school for seven years to do such practical engineering, which almost descends to "craft" rather than engineering---but I am not ashamed to contribute it.

We are intentionally attempting to apply Agile Software Methodology to this development.  That is why we are presently collecting one sqare foot (or 100 watts) or solar energy rather than one square meter (or 600 watts, approximately the power of microwave oven.)  If we cannot build an effective oven that conveniently allows one to cook a very small portion of food, we have no business investing in a larger oven that would be have more potential.

We are currently building a long, narrow CPC because we believe that to build a cooker more convenient for the grill master or chef than those previously developed, we need to achieve higher temperatures.  Existing solar cookery tends to fail because it forces a culturally unappealing change in cooking style. Although I personally am fruitarian(ish) and don't often eat barbecue or hot dogs, that is what Americans cook as a social food at the park.  These foods can be made edible with long, slow cooking typical of solar cookers---but not palatable. The culturally preference is for slighty-charred food what is hot to warm at the center.  To make this experience as similar to what it is with charcoal, we need to produce the same food, and we must produce it in about the same amount of time.  This implies that we must inject heat into the food about as fast as being a few inches above a charcoal fire. Therefore the high concentrations offered by non-imaging optics seems like a reasonable approach.

It is possible that a broader CPC, involute, or other design would be better.  However, "long" CPC seems to be a good compromise in that it allows input into an insulated chamber with a relatively small port, which presumably will allow a higher overall temperature, and the ability to perform "grilling" style cooking in which the heat is primarily radiated rather than conducted into the food.

There are several worthy goals that we can accomplish, though none of them would be considered a theoretic advance of optics:

• We can document our experience trying to make good reflectors.
• We can develop approaches to build complex curves out of widely available tools and materials.
• We can attempt to measure an actual instance of a CPC and compare it to the easily calculated theoretical potential.
• We can develop aiming and positioning technology that is broadly applicable.
  
  But personally, I just think it would be a powerful artifact to build even a single device, at whatever expense, that is as convenient to use a charcoal grill that requires no fuel at all.
   

Rainy Day Construction

Today it rained in Austin.  All day.  Which is good, since we are in a severe drought.  It was not good for measuring the effective of our solar grill, however.

Elliot and I did work a solid seven hours, however, and accomplished two things.  Elliot tested three different adhesive systems for gluing foil to posterboard.  These were rubber cement, heated rubber cement, and contact cement.  All of them look good when first constructed, but our initial experience is that rubber cement eventually wrinkles when you bend it to shape and put it in the sun. I believe that contact cement will keep this from happening, but of course as scientists we don't accept any hypothesis fully until tested---and even then it remains provisional.

The other major work was the completion of our "pressure conformity system."  Previously we had glued the flat panels to the parabolic ribs, creating the shape of a parabola. Unfortunately, this also damaged the ribs, making them essentially unreusable.  Our current system shows great promise.  We constructed aluminum brackets (with a pair of tin snips) that hold the bottom edge of the panel in two little lips, and then we apply pressure downward to the top of the panel with a mirror-holder wired to a turnbuckle.  The pressure pushes it solidly against the ribs, apparently producing a nice parabola.

Clip-and-turnbuckle system (wide angle.)

Mirror clip with wire going over bolt to put force downard and into rib.

Twisted wire through base as a turnbuckle attachment point.

Top of mirror clip pressing down on panel.

 We then performed a "green paper test" of our resulting system using our unpolished panels.  The results are pictured below.  I personally think the drop-off in intensity outside the "cross" pattern is very troubling for our overall concentration.  Next weekend we are hoping to experiment with this more completely. 

Green-paper test with ceiling light. Note strong "cross" pattern and mirror clips on panels.

Another view of the "green paper" test. Note troubling silver voids in the corners.

Green paper test from less than acceptance angle. We believe we should be seeing green everywhere!

Our biggest questions now are:

1. How efficient is our concentrator in absolute quantifiable terms?
2. Are very small deviations from a perfect parabola enough to cause major decreases in efficiency?
3. How much would panels polished to a mirror-like finish improve our concentration?